Subscribe to this blog

Follow by Email

Search AWESOME Stories

"The Big Bang Was A Mirage From A Collapsing Higher-Dimensional Star"

Big Bang was
a mirage from collapsing higher-dimensional star, theorists propose. While the
recent Planck results “prove that inflation is correct”, they leave open the
question of how inflation happened. A new The study could help to show how
inflation was triggered by the motion of the Universe through a
higher-dimensional reality.

The event
horizon of a black hole — the point of no return for anything that falls in —
is a spherical surface. In a higher-dimensional universe, a black hole could
have a three-dimensional event horizon, which could spawn a whole new universe
as it forms.

It could be
time to bid the Big Bang bye-bye. Cosmologists have speculated that the
Universe formed from the debris ejected when a four-dimensional star collapsed
into a black hole — a scenario that would help to explain why the cosmos seems
to be so uniform in all directions.

The standard Big Bang model tells us that the Universe exploded out of an infinitely dense
point, or singularity. But nobody knows what would have triggered this
outburst: the known laws of physics cannot tell us what happened at that
moment.

It is also
difficult to explain how a violent Big Bang would have left behind a Universe
that has an almost completely uniform temperature, because there does not seem
to have been enough time since the birth of the cosmos for it to have reached
temperature equilibrium.

To most
cosmologists, the most plausible explanation for that uniformity is that, soon
after the beginning of time, some unknown form of energy made the young
Universe inflate at a rate that was faster than the speed of light. That way, a
small patch with roughly uniform temperature would have stretched into the vast
cosmos we see today. But Afshordi notes that “the Big Bang was so chaotic, it’s
not clear there would have been even a small homogenous patch for inflation to
start working on”.

In a paper
posted in the arXiv preprint server1, Afshordi and his colleagues
turn their attention to a proposal made in 2000 by a team including Gia Dvali,
a physicist now at the Ludwig Maximilians University in Munich, Germany. In
that model, our three-dimensional (3D) Universe is a membrane, or brane, that
floats through a ‘bulk universe’ that has four spatial dimensions.

Ashfordi's
team realized that if the bulk universe contained its own four-dimensional (4D)
stars, some of them could collapse, forming 4D black holes in the same way that
massive stars in our Universe do: they explode as supernovae, violently
ejecting their outer layers, while their inner layers collapse into a black
hole.

In our
Universe, a black hole is bounded by a spherical surface called an event
horizon. Whereas in ordinary three-dimensional space it takes a two-dimensional
object (a surface) to create a boundary inside a black hole, in the bulk
universe the event horizon of a 4D black hole would be a 3D object — a shape
called a hypersphere. When Afshordi’s team modelled the death of a 4D star,
they found that the ejected material would form a 3D brane surrounding that 3D
event horizon, and slowly expand.

The authors
postulate that the 3D Universe we live in might be just such a brane — and that
we detect the brane’s growth as cosmic expansion. “Astronomers measured that
expansion and extrapolated back that the Universe must have begun with a Big
Bang — but that is just a mirage,” says Afshordi.

The model
also naturally explains our Universe’s uniformity. Because the 4D bulk universe
could have existed for an infinitely long time in the past, there would have
been ample opportunity for different parts of the 4D bulk to reach an
equilibrium, which our 3D Universe would have inherited.

The picture
has some problems, however. Earlier this year, the European Space Agency's
Planck space observatory released data that mapped the slight temperature
fluctuations in the cosmic microwave background — the relic radiation that
carries imprints of the Universe’s early moments. The observed patterns matched
predictions made by the standard Big Bang model and inflation, but the
black-hole model deviates from Planck's observations by about 4%. Hoping to
resolve the discrepancy, Afshordi says that his is now refining its model.

Despite the
mismatch, Dvali praises the ingenious way in which the team threw out the Big Bang
model. “The singularity is the most fundamental problem in cosmology and they
have rewritten history so that we never encountered it,” he says. Whereas the
Planck results “prove that inflation is correct”, they leave open the question
of how inflation happened, Dvali adds. The study could help to show how
inflation is triggered by the motion of the Universe through a
higher-dimensional reality, he says.